l6 OLAF HOLTEDAHL. M.-N. Kl. 



Observations. In spite of the specimens above mentioned all 

 being inferior in size to the average Russian specimens of Strophomena 

 (Rafinesqiiina) imbrex Pand, I have no doubt in referring them to that 

 species. I have before me a large collection of Russian specimen, and 

 among the large, typical specimens are many of dimensions similar to 

 the Norwegian ones, in other respects than size having the characters of 

 the larger. Besides this typical Russian specimen I have before me a 

 large amount of what must be considered a distinct variety (probably 

 var. angustior Schmidt), of very small size, width of hinge line generally 

 about I o mm., and very strongly curved. In many dorsal valves the 

 interior is finely exposed, and shows a minute resemblance to that of the 

 Norwegian specimen depicted above. 



Occurrence 4b (probably transition zone 4 b a — 4 b ß), Bratterud, 

 Bønsnæs, Ringerike. 

 4 b, basal part, zone of Chasmops conicophtahna, Skjæl- 

 bugten, Skien-Langesund district. 



A single free but fragmentary, strongly worn specimen depicted in 

 pi. I, fig. 9 from stage 4 (presumable Coelosphæridiumzone), Blilid in 

 Toten, Mjøsen district, probably also must be referred to Raf. imbrex 

 Pand. It is, however, distinctly less strongly convex than typical Rus- 

 sian specimens. 



Rafinesquina deltoidea Conrad. 

 (PI. I, fig. 2—6.) 



Synonymy in Schuchkrt : Synopsis of American Fossil Brachiopoda. Bull. U. S. G. S. 

 No. 87, p. 338. 



Specimens that exteriorly correspond with this form have been 

 identified from two of the districts of the Kristiania region, viz. from 

 Ringerike and Asker— Bærum. As the specimens from these two districts 

 belong to somewat different types, I consider it convenient to give the 

 descriptions separately: 



Ringerike (figs. 4, 5, 6). 



Mat. pres. A very large number of well preserved specimens 

 in rock. 



Description. Outline rounded triangular, varying very much. 

 The considerable number of specimens show a very markedly angular 

 outline, and a relatively great length. A typical specimen with a greatest 

 width of 23 mm. shows a length of 22. An extreme narrowness is found 

 in a specimen that has a greatest width of 20, a length (of the central disc, 

 not including the deflected margin) of 26 mm. Possibly this specimen has 



